This invention relates to a holding apparatus, in which a holding mechanism is movably supported by an elastic mechanism and, more particularly, to an apparatus for holding a first member, which is coupled to a positioning mechanism for assembling the first and a second members.
An automatic assembly system for automatically assembling a first member such as a piston and a second member such as a cylinder has been proposed in U.S. Pat. No. 3,824,674, in which various holding apparatus have been described. All those holding apparatus provide springs placed parallel to a center axis of a drive shaft, which is coupled with a holding mechanism through springs, so as to detect a displacement or a deflection of the holding mechanism from the drive shaft, even if a small force in comparison with a total weight of the holding apparatus and a first member held thereby is effected to the first member. In a case that the first member, however, is relatively heavy in weight, the springs must be large in size and in elastic modulus. Accordingly, if a sensitivity of a detector for the displacement or the deflection is constant, the springs must be longer in length in order to produce a minimum value of the displacement or the deflection which the detector can detect, so that the holding apparatus may become large and may not be sensitive in its operation, whereas if the springs are constant in size and in elastic modulus, a detector having high sensitivity is required so that the holding apparatus may have a high cost. Further, it is more difficult to insert the piston into the cylinder when the springs become large in size and in elastic mechanism.